Barrister John Pemberton, must have been sufficiently convinced that investment in the Llanelli coalfield would provide high profits, because by 1803 he generally advertised the fact that he had £20,000 available for industrial development.

Pemberton formed an amicable relationship with William Roderick, who was by this time in severe financial difficulties. Following discussions in 1803 the Pembertons took possession of the Bres pit and were allowed to use Roderick, Bowen and Griffith’s Wern Canal and their shipping place.

As early as 1804, Charles Nevill, Managing Director, of the Copperworks, was not impressed and voiced the opinion that the Pembertons were speculators and would not be able to meet their commitments.

The following year, William Hopkin, Sir John Stepney, 8th Baronet’s Agent, was complaining that the Stepney Estate was not receiving anticipated income from royalty payments.

Between 1812 and 1816 the Pembertons had acquired lands at Llwyncyfarthwch, that had once belonged to Dorothy Vaughan following the Deed of Partition, and from John Rees of Cilymaenllwyd.

By 1813, undeterred by criticism, members of Pemberton family, including Frances, Christopher, Richard (senior), John, Ralph Stephen, Richard (junior) and Thomas, were involved in developments in Llanelli and Pembrey. They invested heavily, working the Bres and Talsarnau pits, holding an interest in the railway from the Wern to Seaside and using Roderick Bowen and Griffith’s original dock. The dock that had belonged to Roderick and partners was enlarged and became known as Pemberton’s Dock.

In 1813 Francis and Christopher Pemberton were proposed as Harbour Commissioners and promoted the Kidwelly and Llanelly Canal Company.

By 1817 the Pemberton enterprises were well established and they were issuing their own banknotes from Pemberton Mansion and advertised that their coal trade required 5,000 tons of shipping.

They planned to sink a new pit at Llwyncyfarthwch (where Coedcae district is today). The Llwyncyfarthwch Pit was also known as Park Pit and was later re-named Pemberton Pit.

By 1820 the Pembertons were planning a railway system to carry their coal to Pembertons’ Dock and decided on a route which involved a tunnel through high ground at Marble Hall between their pit and the Wern.

However, like the William Roderick Partnership, the Raby’s and General Warde, the Pembertons had over-stretched themselves and by 1828 had decided to withdraw. They placed an advertisement in 1829 for the sale or letting of the Llanelly Colliery – comprising the Bres and Talsarnau working pits, drained by a powerful steam engine. Particulars were available from ‘Ralph S Pemberton, Llanelly; R Pemberton, Holborn, London, or Thomas Pemberton, Sunderland’.

They quickly found a taker and George Bruin of Hermes Hill, Pentonville, London, purchased all the Pemberton industrial interests at Llanelli.

Ralph Stephen Pemberton actually lived in Llanelli and resided in the Pemberton Mansion which was situated where the Athenaeum was later built. The Athenaeum later became Llanelli's Public Library. He probably left the area in 1829, ending the family’s 25 year direct involvement in Llanelli’s coal industry.

Although they met with only limited success, the Pembertons contributed significantly to Llanelli’s early 19th century development. It is not clear which members of the family were directly connected with Llanelli’s coal industry. However, it seems that John Pemberton was involved in the initial negotiations leading up to their operations at Llanelli. The Pemberton family are remembered by the present day name of the district of Pemberton (Llandafen) and Tunnel Road in the Wern district.